Stability Problem of Wave Variable Based Bilateral Control: Influence of the Force Source Design

Abstract

The wave variable has been proposed to achieve robust stability against the time delay in bilateral control system. However, the influence of the force source on the overall system is still not clear. This paper analyzes this problem and proposes a supplement to the stability analysis for wave variable based bilateral control. Based on the scattering theory, it is pointed out that the design of force source decides the passivity of the two-port network of slave robot. This passivity influences the stability of overall system. Based on the characteristic equation and small gain theorem, it is clear that inappropriate designed force source in encoding the wave variable destroys the stability in the presence of time delay. A wave domain filter makes up for the broken stability. The principle of this reparation is explained in this paper. A reference is also provided by the analysis to design the parameter of the wave domain filter. Experiments prove the correctness and validity.

Adaptive-observer-based robust control for a time-delayed teleoperation system with scaled four-channel architecture

“…In addition, the literature reveals that very few methods apply direct force signals reflection in the nonlinear teleoperation system under time delays, although the force reflection can greatly enforce the realistic haptic perception felt by the operators and increase the system transparency. The reason is that the design of the force source and the transmission of the external force signals in delayed communication channels may adversely affect the passivity of the communication channels and jeopardize the stability of the teleoperation system using the passivity-based controllers [38]. Therefore, designing control strategies to accurately derive external force signals and transmit command signals without jeopardizing the system stability is a big challenge for bilateral teleoperation.…”